(1) Field of the Invention
Subject invention is related to underwater towed bodies and more particularly to an apparatus and method for stabilizing an underwater towed body by correcting for its rolling motion.
(2) Description of the Prior Art
Traditionally, an underwater towed body is stabilized against its rolling motion caused by the tow cable torque. This is accomplished by either a correcting moment of a weight used as a keel, or by the use of ailerons controlled by a roll sensor. Usually, the tow cable used for a towed body is not torque balanced and a slip joint connection between the towed body and the tow cable is not considered desirable as a water tight slip joint is expensive, complex, and likely to contaminate the acoustic sensor signals. A stabilizing device using a keel to correct for coarse rolling motion of an underwater towed body and horizontally moveable trim weight inside the towed body to correct for the finer rolling motion is described in our copending patent application filed with the same filing date as that of subject patent application. That arrangement is suitable for a tow cable which is not excessively torque unbalanced. For tow cables that twist excessively under load, that device does not work very well. There is thus a need for a stabilizing device which can compensate for large rolling motions of the towed body due to the torque of the tow cable.